Week 13: (C) Coupling and Skeletal Muscle Contraction Flashcards
What does an excitation contraction trigger?
triggers an increase in Ca2+ concentration
What is excitation contraction also known as?
E-C coupling
What is the plasma membrane also called?
sarcolemma
What is the sarcolemma?
display invaginations that extend from surface of membrane to muscle cell
membrane of muscle fibre
What are these tubules called?
Transverse tubules (T tubules)
What muscle fibres has T tubules?
skeletal & cardiac
Where do the T tubules penetrate the muscle cells?
2 points in each sarcomere at junction of A and I bands
What do the T tubules associate with?
2 cistermma
What is the cistermma?
specialised regions of the sarcoplasmic rectilium
muscles version of ER
What organelle stores Ca2+ ions?
Sarcoplasmic rectilium
What is the TRIAD?
The combination of the t-tubule with the 2 cistermma
What is depolarised in the TRIAD?
T-tubule membrane
Where is Ca2+ released from?
Sarcoplasmic rectilium at the TRIAD
What organelle has the L-type Ca2+ channels?
T-tubules
What is an L-type Ca2+ channel?
They are a tetrad
cluster of 4
voltage gated
why do we have T-tubules?
need to covert a chemical signal to a physical one
provide a means of rapidly transmitting the action potential from the surface into the central portion of the muscle fibre
What opens the L-type Ca2+ channels?
depolarisation
What is DHP?
Another name for the L-type Ca2+ channel
What does depolarisation of the membrane do to DHP?
confo change
What are the effects of the conformational change of L-type Ca2+ channel?
confo change allows Ca2+ to enter
A confo change in a another channel called Ca2+ release channel
Where is the Ca2+ release channel located?
SR
What can inhibit the Ca2+ release channel?
ryanodine& caffine
How do the L-type and release channel attach?
release channels face the T tubules
The foot of the release channel is close to one of the L-type
What happens once coupling occurs between receptors?
Ca2+ released into the cytosol
